Field of the Invention and Prior Art
The invention relates to improvements in tractor-trailer rigs of the fifth-wheel semi-trailer type.
Tractor-trailer rigs having a fifth-wheel coupler and a semi-trailer having a complementary coupler comprising a wear plate and a coupling pin projecting downwardly from the wear plate and providing, when the rig is coupled, an axis about which the rig is articulated, are well known and are commonly preferred to provide an extremely wide angle of articulation. Thus, the tractor, in effect, can be swung from a position at right angles to or past right angles to the center line of the rig around to the other side an equal distance. Thus is necessary in order to make possible the proper maneuvering of the semi-trailer. Thus wide angle of articulation, however, has an undesirable consequence in that the rigs are susceptible to jackknifing under certain circumstances, particularly when the weather is bad and the roads are slick.